Signaling system



March 7, 1933. J. M. KANE SIGNALING SYSTEM Filed March 15, 1931 Qwmmto o James fi a/ze.

Patented Mar. 7, 1933 11m I.- m BERKELEY, CALIFORNIA sremmrno svsrmr Application filed larch '18, 1981. Serial Ho. $22,488.

(cam mn'm no: or men a, 1888, as man nan. so, 198M870 o. c. 151) My invention relates broadly to telegraphic signaling systems and moreparticuarly to high speed telegraphic signaling iystems having means for. eliminating inter- I erence from static and other interfering signals.

One of the objects of my invention is to rovide a signaling system in which the efects-of static an interfering signals may 0 be substantially reduced and si al receiving" circuits operated through suc static and interference.

Another object of my invention is to provide a telegraphic receiving circuit having 5 means for operating a relay for reproducing transmitted telegra hic signals irrespective of static and other interference, even under conditions where thestatic and interference 80 mai be of relatively large amplitude and of sue a character as to render the operation.

of other types of receiving systems impractical as heretofore known;

Still another object of my invention is to provide an arrangement of electron tube cir- 'cuits adapted to be connected to the audio frequency output of a radio receiving s stem and operating a signal receivin re ay wherein the electron tube circuits alance out the effects of static and interferin signal energy while amplifying the desire signalling energy and positive y actuating the re ay. H

A furtherobject of my invention is to provide an audio frequency am lifier system having a pair of independent ranches with -a relay including a pair of actuating windings, one of said win being in magnetic association with each 0 said branches with means for balancing the effects of static and 40 interferin signalin energy while amplifying the e ects of t e signaling energy for operating said relay system without interference from the static and undesired signaling energy. 7 Other and fu ther objects of my invention reside in the arran inent of branch circuits of an amplifier an relay system as set forth more fully in the specification hereinafter following by reference to the accompanying 6-0 drawing which diagrammatically illustrates the amplifier and relay systemof my inven- 1 tion.

' A single frequency can be re'ectedfrom a circuit with greater facility t an a single frequency can be accepted with all others both above and below rejected. Hence it is proposed to rovide two branch circuits, one of which substantially entirely rejects the si al frequency yet transmits readily all 0 the other frequencies comprisin the interference, and-the other branch clrcuit of which transmits readil the signal frequency yet rejects in part the requencies com rising the interference. The output of the ranch that transmits the interference frequencies alone and the out ut of the branch that transmits thesignal vrequency and some of the interference frequencies are brought together in phase opposition to efi'ect the balancin out or neutralization of the interfer I encerequencies, while permitting the signal frequency-alone to affect the recor ing device. The circuit arrangement of my invention is based upon the selective audio tuning of a pair of branch circuits associated with the output of the audio frequency amplifier in a signal receiving system by which undesiredstatic energy an interfering signal energy may be eliminated. The system of my invention comprises an amplifier having an input stage adapted to resolve the incoming signal volta e into two components and selectively amphfythese components in separate branches of the amplifier system. v One branch is arranged to amplify all the varia- 5 tions in the input voltage at the terminals of the audio frequency amplifier except the variations in the voltages of the desired signal ener The second branch is arranged to ampli the desired signaling energy as much as possible, together with such other voltages that pass through the audio tuning fi1ters.- The first branch circuit is coupled through an audio frequency amplifier to a circuit whose outputis controllable, connections being provided between such circuit and a vacuum tube system whose grid is driven positive b an increase in energy through the first ranch circuit. In. other words, as the amplitude of the undesired sig- 1 naling energy, static and interference, increases the average plate current through the control tube circuit tends to increase. In the second branch circuit, in which the desired signal energy and interference is amplified, a coupling is provided to the id of i the same electron tube that is contro ed by the first branch circuit though in such manner that any voltage in the second branch will tend to decrease the average plate current through the tube. Summarizing the, above general statements, any tendency that the interference voltage may have to increase the ate current through the control tube will n ofiset b the tendency of the voltage in the second ranch to decrease the same plate current. By accurate adjustment of voltage values the resultant change of plate current through the control tube due to interference contained in each of the branches be Zero. The desired signal in the second branch generating no counter-force in the first branch will cause a change of plate current in the control tube and the actuation of the relay system for the closing of a control circuit to any desired recorder, such as a teletype automatic printer or ink register.

Referring to the drawing in detail, reference character 1 designates an input audio frequency transformer having a primary winding 2 and a secondary winding 3, the primary winding 2 being connected through terminals la and it with the output of an audio frequency amplifier system of a signal receiving aparatus. A power amplifier tube 4 is provid to receive all of the audio frequency signal components and the static and interfering ener components and increase the amplitude t ereof. The output of the ower amplifier tube a is connected to two independent branch circuits through separate transformers (Sand 7. Transformer 6 has its prima winding 8 coupled with its secondary win ing 9. The primary winding 8 has the primary winding of a second transformer 10 shunted there-across, across the secondary of which-is connected a variable condenser 11 to tune this-winding therebymakingit operate to reject from the first branch circuit the desired signal components while selectively responding to the undesired signal components. The output of the transformer 6 is connected to the input of electron tube 12 which includes meter 14 in'th'e output circuit thereof, the output of tube 12 bemg coupled through transformer 15 with the input of the succeeding tube 16. The amphtude of the undesired signaling energy, static and interference, is increased by the amplification characteristics of tubes 12 and 16 and delivered through transformer 17 to the output control circuit which I have designated generally-at 18. The output control circuit includes a variable resistor 19 connected in shunt with the secondary winding a. genre nected tov one terminal of the control circuit 18. The output of the control tube 22 includes the winding 23-01? the polarized relay system 24 in which the actuatin winding 25is arranged adjacent thewinding 23 for controlling the operation of the armature .26 in the field of the permanent magnet system 27. Armature 26 operates'the moving contact system 28 for establishing connection with fixed contacts 29 and 30. The control .tube 22 operates with a highplate current obtained rom the source 31. A greater voltage will be uired to increase the current than will be required to decrease the current in the output circuit of the control tube. Consequently the tube 16 and the transformer shunt 19 are necessary to permit the adjustment of the interference voltage in the first branch circuit to such a value that its eilect in the plate circuit of -tube 212 ofisets that applied in the opposite direction by the control tube 32 in the second branch circuit.

Thecontrol tube 32 in the second branch circuit includes a cathode 320, a control grid 32b, and an anode 320'. The input circuit of the control tube 32 is completed through the secondary winding 33 of the transformer 7 constituting a part of the second branch circuit in the output circuit of the power amplifier tube 4'. The transformer 7 has its primary winding 34 connected to a transformer system 35 in which one winding thereof iss unted by' means of a tuning condenser 36 which serves with the transformer system 35 as an audio frequency filter by means of which the interference, static and undesired signaling components, are rejected from the second branch circuit permittin the second branch circuit to res ond to the esired audio frequency signal. y manipulation of the rejector 35-36 the second branch circuit may be made, to respond to the desired signal excludin undesired signaling energy and static w ile manipulation of the filter constituted bv transformer 10 and condenser 11 enables the first branch circuit to respond to. the undesired signalin energy, static, and interference to the exe usion of the de-J sired signaling energy. 'The input circuit of the control tube 32 in the second branch circuit is completed by means of a tap 37 on potentiometer 38 which is connected in shunt with the source of biasing tential 39, a'connection returning from t e biasin circuit through lead 40 to the cathode 32a 0 the control tube 32.. The biasing potential source 39 &

potential designated as 43.

The output circuit of the control tube 32 includes the meter 44, the winding of the polarized relay 24, the impedance or resistor 45, and the high potential source 46. The plate potential for the tubes 4, 12 and 16 is obtained through connection 47 to the point 48 in the output circuit of the control tube 32 adjacent the high potential source 46. The cathode 22a of the control tube 22 is heated from a separate potential source indicat-ed at 49. In the particular arrangement illustrated, I have shown the control leads of the relay system brought out to the marking, spacing and timing terminals 50, 51 and 52 leading to the fixed contacts 29 and and movable set of contacts 28 as shown. The windings 23 and 25 of the relay system 24 operate conjointly upon movable armature 26 for effecting the positive closing of .the contacts without interference from static and undesired signaling energy.

It will be observed that the input circuit of the control tube 22 is completed through a portion of the output circuit of the control tube 32, that is to say, the control grid 22b connects to the end of the secondary winding 20 of the transformer 17, the o posite end of which is connected through s idable contact 210 on potentiometer 21b to the point 54 in the output circuit of control grid 32. The connection 54 is immediately adjacent one end, of the impedance or resistance 45, the other end of which at is connected through lead 56 to the cathode 22a for completing the input circuit connections to the tube.

This arrangement provides for the raising of the average grid voltage on control grid 22b when input signal energy is received in the first. branch circuit. The raising of the average grid voltage on grid 22b results inan increase of the average plate current in the output of control tube 22. Any tendency the interference voltage may have to increase -the plate current in tube 22 will be offset by the tendency of the interference voltage in the second branch circuit to decrease the same plate current. By accurate adjustment terminals 10. and 1?) from the audiofrequency amplifier system of the signal receiver.

The bias potential on control grid 32b of con-.

trol tube 32 is adjusted by movement of contact 37 on potentiometer 38 so that meter 44 in the output circuit of control tube 32 readszero. The bias potential on the grid 22b of tube 22 is ad'usted by movement of contact 21c'on potentiometer 215 until the meter 53 in the output circuit of control tube- 22 reads a redetermined calibrated value. I haveseected for this reading three milliamperes in an apparatus which I have successfully constructed and operated. After completing these adjustments the input terminals 1a and 1b of the relay system are connected to signal receiving apparatus. The filter circuit constituted by transformer. 10 and variable condenser 11 is then adjusted by moving the audio tuning control at 11 whereby the desired signal is eliminated from the first branch circuit while permitting the passage of the undesiredsignal, static, and interfering signaling energy. Under this condition the meter 14 in the output circuit of tube 12 in the first branch circuit responds only to interference. By adjustment of the audio frequency tuning control constituted by the variable condenser 36 which is connected to the audio frequency transformer system 35, the interference, including static and undesired signal is somewhat suppressed enabling the second branch circuit to respond to the desired signaling energy at its maximum, so that the meter 44 of the control tube 32 responds to the desired signaling energy. By manipulation of the transformer shunt 19, the circuits are -vo'ltage in the first branch circuit to such a value that its effect in the plate circuit control of tube 22 will offset the effect of the interference existing in the circuit of control tube 32. 7 It will-be observed that the opposite effect of the interference is not due toany magnetic reaction of one field upon another with a view of canceling the effect of such fields. The interference is actually separated into two independent circuits each of which connect to the relay windings 23 and 25. However, the interference will have no effect upon themovement of the relay armature26 as the amplitudeofthe interferin effects will be the same in both relay win .ings. The signal energy however whichis totally absent in the first branch circuit is effective in the second branch circuit to operate the relay armature 26.

Adjustments of this circuit are relatively simple. The milliameters are used as indicators rather than the usual headphones, for when using the latter it is difiicult to note an exact resonant condition because of the large currents encountered. The milliameters are better indicators of resonance than headphones.

To show the facility with which this cir-- cuit can cancel out interference, tune the second branch circuit to the frequency of the desired audio signal. With a local audio oscillator being controlled by contacts 50 and 51 and reproducing themodulations of the desired signal, tune the first branch circuit to the same frequency as the second branch circuit. The action' of the relay will cease, and the meter 53 of tube 22 will show no change of current, si ages applied to the grid of tu e 22, via trans-v former 17 and resistance are equal in potential and 180 degrees out of phase. I

The principle of operation of my. invention may be clearer by considering the control tube 22 as a holding over tube while the control tube 32 may be considered as the signal tube. Because of the interlinking of the in ut circuit of the holdingover tube 22 with t e output circuit of the signal tube 32, a r se of plate current in the output of the signal tube 32 due to an incoming signaling impulse operates to decrease the current in the plate circuit of the holding over tube 22.

- However, the interference and static ener' incident upon the input circuit of the holding over tube 22 tends to increase the plate cur rent. The actual plate current through winding 23 is therefore a differential be.- tween the desired signal energy and the integraton of the undesired signal energy and static. Because of the fact that the signal persists in addition to and separate and distinct from the interference, the signal energy --will actuate the relay armature 26 and effect potential on the grid 22?) of tube 22. Thenegative potential on the grid 22?)" from tube 32 consisting of interference is ofiset by the interference having a positive potential comifyin that the Volt rename ing from tube 16 via transformer secondary 20. These two voltages of opposite polarity, then, cancel out and no plate current charge through tube 22 results from interference. The negative voltage coming from tube 32 consistin of desired signal finds no counte voltage 0 an opposite clarity from tube and transformer secon ary. 20, sothe negative signal voltage decreases the potential of grid 26b causing a decrease of plate current through tube 22 and coil 23, coincident with an increase of current through tube 32 and coil 25. Thus coil 25 operates the relay arm until the signal through tube 32 decreases coincident with an increase of current through tube. 22 and coil 23, when 23.operates the arm 28.

I have found the a paratus of myinve'n riods. The apparatus of my invention re-- sponds to the rapid fluctuations in signal voltage such as represented by the Baudot code of printing telegra h systems, and acheavy static cordingly is highly use ul as a connecting link between the radio receiving apparatus and the automatic printing apparatus of a high s eed radiortelegraph system.

Whi e I have described my invention in one of its preferred embodiments, I desire that it be understood that modifications may be made and that. no limitations upon my invention are intended other than are imposed by the scope of the ap ended claims.

The invention described herein, if patented may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a signal receiving system, an input circuit, a pair of branch circuits extending from said input circuit, one of said branch circuits having means discriminating against the desired signaling energy while transmitting undesired signaling energy and interference and the other of said paths having means discriminating against interference and undesired signaling energy while transmitting the desired signaling energy, a pair of control tubes each having input and output circuits with the input circuits thereof individually connected to each of said paths, a relay system including a movable armature and a pair of actuating-windings, means interconnecting the output circuit of each'control tube with a selected winding, a resistance element included in the output circuit of one of said control tubes and connections across said resistance element with the input circuit ot' the other of said control tubes for differentially energizing said control tubes for etlecting a balancing operation of said actuating windings with respect to the undesired signaling energy and interference while controlling the movement of said armature under control of the signaling energy.

2. In a signal receiving system, an input circuit, a pair of branch circuits extending from said input circuit, one of said branch circuits having means discriminating against the v desired signaling energy while transmitting undesired signaling energy and interference and the other of said paths having means discriminating against interference and undesired signaling energy while transmittingthe desired signaling energy, a relay system including a movable armature and a pair of actuating windings, a pair of control tubes each having input and output circuits, a control grid in each of said control tubes, the

output circuit of one control tube including one of said actuating windings and the output circuit of the other of said control tubes including theother of said actuating windings, the input circuit of said first mentioned control tube being connected to said first mentioned branch circuit, the input circuit of the other of said control tubes being connected with the other of said branch circuits and connections between the output circuit of said last mentioned control tube with the' input circuit of said first mentioned control tube for producing a current drop in the output circuit of said first mentioned control tube due to the impression of signaling energy upon the control grid of said second mentioned control tube for opposing an increase of output current in said first mentioned control tube due to the impression of undesired signaling energy and interference on the input circuit thereof for effecting movement of said armature under control of the signaling energy.

JAMES M. KANE. 

